From: Brian Lodwick (xpranax@xxxxxxxxxxx)
Date: Sun Oct 07 2001 - 17:42:39 GMT-3
No sweat guys. Minimal payback for the information I've received from this
list.
After I read through what I wrote I noticed a mistake. In my message I
meant to say "Aparently you must either have a fully meshed topology for
ISIS (not a hub spoke) or you must ensure all next hops are neighbors by
using point-to-point sub-interfaces all around. My example did not work
because spoke to spoke as next-hops were not neighbors."
Also an additional piece of information that I thought was interesting. In
an ISIS "broadcast network" a DR or more appropriately in ISIS terms a
Designated IS will be elected, but an interesting difference from OSPF is in
this environment with a Designated IS, adjacencies will be formed between
all neighbors not just between the Designated IS and non-Designated IS's.
The Designated IS's function is to ensure the flooding of LSP's is reliable.
(Doyle vol.1 pg.607)
>>>Brian
"If A equals success, then the formula is: A=X+Y+Z. X is work. Y is play. Z
is keep your mouth shut."
- Albert Einstein
>From: "Lopez, James" <james.lopez@atosorigin.com>
>To: "'Brian Lodwick'" <xpranax@hotmail.com>
>Subject: RE: ISIS over ATM multipoint FIXED for anyone interesed
>Date: Sun, 7 Oct 2001 15:23:19 -0400
>
>Thanks for sharing this!!!
>
>-----Original Message-----
>From: Brian Lodwick [mailto:xpranax@hotmail.com]
>Sent: Friday, October 05, 2001 5:40 PM
>To: ccielab@groupstudy.com
>Subject: ISIS over ATM multipoint FIXED for anyone interesed
>
>
>I read through all kinds of stuff and finally found an excerp at the bottom
>of a cisco case study on OSPF. The excerp just said in ISIS all next hops
>must be neighbors. In OSPF this is not true though because you can use
>frame
>
>maps. Aparently you must either have a fully meshed topology for ISIS, not
>a
>
>hub spoke because all of the other spokes as next-hops are not neighbors. I
>thought that was pretty interesting though and wanted to share it with
>anyone interested. I have copied the excerp from the case study and the
>link. I also included the new configs and the routing tables.
>I did just like Raymond suggested, and instead of having a multipoint
>sub-interface on the hub I put 2 point-to-point sub-interfaces on there to
>overcome the shortfall of ISIS, and everything is working.
>Just a little caveat I guess to remember for ISIS. I am going try to use
>point-to-point sub-interfaces on any hub spoke topologies when using ISIS.
>Another thing I dug up when researching this issue. I remembered in Bruce
>Caslow's class he quickly said that there are 2 combinations that don't mix
>when using ISIS on an NBMA network. Cannot use point-to-point
>sub-interfaces
>
>and a physical interface together, and you cannot use a point-to-point
>sub-interface with a multipoint sub-interface, but you CAN use a physical
>interface and a multipoint sub-interface config together. The reasoning
>behind this was realized today while reading Jeff Doyle's Routing TCP/IP
>when it said ISIS only describes 2 network types - Broadcast and
>Point-to-Point. The problem is obvious if you've been working with OSPF
>much. Broadcast will attempt to elect a Designated IS and in Point-to-Point
>it won't. If you configure an interface in a NBMA network (such as
>Frame-Relay or ATM) with a multipoint sub-interface or right on the
>physical
>
>interface it will be considered a "Broadcast network type" in ISIS, and the
>only type of interface considered a "Point-to-Point network type" in an
>NBMA
>
>network is a point-to-point sub-interface. Anyways here's the stuff, hope
>it
>
>helps someone else. Thanks for everyones help and ideas!
>
> >>>Brian
>
>
>
>http://www.cisco.com/warp/public/104/ospfdb4.html
>The Next Hop on Nonbroadcast Multiaccess Networks
>To explore the issue of the next hop in a nonbroadcast multiaccess (NBMA)
>network, let's take the following example. There are three routers on a
>transit network (Routers non_DR_a, non_DR_b, and DR). It's a hub and spoke
>topology on an NBMA media such as Frame Relay, Asynchronous Transfer Mode
>(ATM), or X.25.
>
>
>
>When Router non_DR_a calculates routes through Router non_DR_b, it makes
>Router non_DR_b the next hop. However, Router non_DR_a doesn't have a
>virtual circuit (VC) to Router non_DR_b, which means these routers can't
>even ping each other. This means OSPF is installing routes into the routing
>table with a next-hop that can't be reached.
>
>The solution to this problem is to add a second frame-relay map statement
>to
>
>make all the neighbors reachable through the VC going to Router DR. For
>example:
>
>interface Serial0
>frame-relay map ip 1.1.1.1 700 broadcast
>!-- This is a map for the DR
>frame-relay map ip 1.1.1.2 700 broadcast
>!-- This is a map on the same VC data-link connection
>!-- identifier (DLCI) for a non-DR router
>
>Let's compare this behavior with that of the Intermediate
>System-to-Intermediate System (ISIS) protocol. A router won't install an
>ISIS route through a next hop, unless the next hop is a neighbor. This
>means
>
>ISIS won't work on a multi-point interface unless the routers are fully
>meshed.
>
>OSPF installs routes even though the next hop isn't a neighbor, and isn't
>reachable through Layer 2. However, you can fix this problem by configuring
>multiple map statements.
>
>Hub:
>r8#sh run
>Building configuration...
>
>Current configuration : 1284 bytes
>!
>version 12.1
>no service single-slot-reload-enable
>service timestamps debug uptime
>service timestamps log uptime
>no service password-encryption
>!
>hostname r8
>!
>logging rate-limit console 10 except errors
>!
>!
>!
>ip subnet-zero
>!
>!
>no ip finger
>no ip domain-lookup
>!
>no mgcp timer receive-rtcp
>!
>!
>call rsvp-sync
>!
>!
>!
>!
>!
>!
>!
>!
>interface ATM2/0
>no ip address
>no atm scrambling cell-payload
>atm uni-version 3.1
>no atm ilmi-keepalive
>!
>interface ATM2/0.1 point-to-point
>ip address 172.16.70.6 255.255.255.252
>ip router isis
>pvc 7/15
> protocol ip 172.16.70.5 broadcast
> protocol clns 49.0000.0007.0007.0007.00 broadcast
>!
>isis circuit-type level-2-only
>!
>interface ATM2/0.2 point-to-point
>ip address 172.16.70.2 255.255.255.252
>ip router isis
>pvc 8/15
> protocol ip 172.16.70.1 broadcast
> protocol clns 49.0000.0002.0002.0002.00 broadcast
>!
>isis circuit-type level-2-only
>!
>!
>router isis
>net 49.0000.0008.0008.0008.00
>!
>ip kerberos source-interface any
>ip classless
>no ip http server
>!
>!
>!
>!
>!
>!
>!
>!
>!
>!
>snmp-server engineID local 80000009FF0000A100E4E5B4
>snmp-server manager
>!
>dial-peer cor custom
>!
>!
>!
>!
>alias exec ip sh ip route
>alias exec int sh ip int brief
>alias exec ipx sh ipx route
>!
>line con 0
>transport input none
>line aux 0
>line vty 0 4
>login
>!
>end
>
>r8#ip
>Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter
>area
> * - candidate default, U - per-user static route, o - ODR
> P - periodic downloaded static route
>
>Gateway of last resort is not set
>
> 172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
>i L2 172.16.20.0/28 [115/20] via 172.16.70.1, ATM2/0.2
>C 172.16.70.0/30 is directly connected, ATM2/0.2
>C 172.16.70.4/30 is directly connected, ATM2/0.1
>
>
>
>
>
>Spoke:
>r7#sh run
>Building configuration...
>
>Current configuration : 1958 bytes
>!
>version 12.1
>no service single-slot-reload-enable
>service timestamps debug uptime
>service timestamps log uptime
>no service password-encryption
>!
>hostname r7
>!
>logging rate-limit console 10 except errors
>!
>!
>!
>ip subnet-zero
>!
>!
>no ip finger
>no ip domain-lookup
>!
>no mgcp timer receive-rtcp
>!
>!
>call rsvp-sync
>!
>!
>!
>!
>!
>!
>!
>controller T1 1/0
>framing esf
>linecode b8zs
>channel-group 0 timeslots 1-24
>!
>controller T1 1/1
>!
>!
>interface ATM0/0
>no ip address
>no atm scrambling cell-payload
>no atm ilmi-keepalive
>!
>interface ATM0/0.1 point-to-point
>ip address 172.16.70.5 255.255.255.252
>ip router isis
>pvc 5/15
> protocol ip 172.16.70.6 broadcast
> protocol clns 49.0000.0008.0008.0008.00 broadcast
>!
>isis circuit-type level-2-only
>!
>interface Serial1/0:0
>no ip address
>encapsulation frame-relay
>frame-relay traffic-shaping
>!
>interface Serial1/0:0.1 point-to-point
>ip ospf network point-to-multipoint
>!
>interface Serial1/0:0.2 multipoint
>ip address 172.16.30.1 255.255.255.0
>ip ospf network point-to-multipoint
>frame-relay interface-dlci 701
> class vofr
> vofr cisco
>frame-relay interface-dlci 703
>!
>!
>router ospf 100
>log-adjacency-changes
>network 172.16.30.1 0.0.0.0 area 0
>!
>router isis
>net 49.0000.0007.0007.0007.00
>!
>ip kerberos source-interface any
>ip classless
>no ip http server
>!
>!
>!
>!
>!
>!
>!
>!
>!
>!
>map-class frame-relay vofr
>no frame-relay adaptive-shaping
>frame-relay fair-queue
>frame-relay voice bandwidth 32000
>frame-relay fragment 80
>!
>snmp-server engineID local 80000009FF0000A1012D34BF
>snmp-server manager
>!
>voice-port 3/0/0
>!
>voice-port 3/0/1
>!
>voice-port 3/1/0
>!
>voice-port 3/1/1
>!
>dial-peer cor custom
>!
>!
>!
>dial-peer voice 777 pots
>destination-pattern 777
>port 3/1/0
>!
>dial-peer voice 111 vofr
>destination-pattern 111
>session target Serial1/0:0 701
>!
>!
>alias exec ip sh ip route
>alias exec int sh ip int brief
>alias exec ipx sh ipx route
>!
>line con 0
>transport input none
>line aux 0
>line vty 0 4
>login
>!
>end
>
>r7#ip
>Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter
>area
> * - candidate default, U - per-user static route, o - ODR
> P - periodic downloaded static route
>
>Gateway of last resort is not set
>
> 172.16.0.0/16 is variably subnetted, 7 subnets, 5 masks
>O IA 172.16.50.0/29 [110/84] via 172.16.30.2, 00:31:26, Serial1/0:0.2
>O 172.16.30.2/32 [110/74] via 172.16.30.2, 00:31:26, Serial1/0:0.2
>O 172.16.30.3/32 [110/74] via 172.16.30.3, 00:31:26, Serial1/0:0.2
>C 172.16.30.0/24 is directly connected, Serial1/0:0.2
>i L2 172.16.20.0/28 [115/30] via 172.16.70.6, ATM0/0.1
>i L2 172.16.70.0/30 [115/20] via 172.16.70.6, ATM0/0.1
>C 172.16.70.4/30 is directly connected, ATM0/0.1
>
>
>Spoke:
>r2#sh run
>Building configuration...
>
>Current configuration : 2519 bytes
>!
>version 12.2
>no service single-slot-reload-enable
>service timestamps debug uptime
>service timestamps log uptime
>no service password-encryption
>!
>hostname r2
>!
>logging rate-limit console 10 except errors
>!
>ip subnet-zero
>no ip finger
>no ip domain-lookup
>!
>ip cef
>no ip dhcp-client network-discovery
>frame-relay switching
>call rsvp-sync
>!
>!
>!
>!
>!
>!
>!
>controller T1 0/0/0
>framing esf
>clock source internal
>linecode b8zs
>channel-group 0 timeslots 1-24 speed 56
>!
>controller T1 0/0/1
>framing esf
>linecode b8zs
>!
>controller T1 0/0/2
>framing esf
>linecode b8zs
>!
>controller T1 0/0/3
>framing esf
>linecode b8zs
>!
>!
>interface Serial0/0/0:0
>no ip address
>encapsulation frame-relay
>no ip route-cache distributed
>frame-relay intf-type dce
>frame-relay route 701 interface Serial3/1 107
>frame-relay route 703 interface Serial3/2 307
>!
>interface Ethernet0/1/0
>ip address 172.16.20.1 255.255.255.240
>ip router isis
>no ip route-cache distributed
>no keepalive
>isis circuit-type level-1
>isis hello-multiplier 1000
>isis hello-interval 300
>!
>interface Ethernet0/1/1
>no ip address
>no ip route-cache distributed
>shutdown
>!
>interface Ethernet0/1/2
>no ip address
>no ip route-cache distributed
>shutdown
>!
>interface Ethernet0/1/3
>no ip address
>no ip route-cache distributed
>shutdown
>!
>interface ATM1/0
>no ip address
>no atm ilmi-keepalive
>!
>interface ATM1/0.1 point-to-point
>ip address 172.16.70.1 255.255.255.252
>ip router isis
>pvc 6/15
> protocol ip 172.16.70.2 broadcast
> protocol clns 49.0000.0008.0008.0008.00 broadcast
>!
>isis circuit-type level-2-only
>!
>interface ATM2/0
>no ip address
>shutdown
>no atm ilmi-keepalive
>!
>interface Serial3/0
>no ip address
>shutdown
>!
>interface Serial3/1
>no ip address
>encapsulation frame-relay
>frame-relay intf-type dce
>frame-relay route 107 interface Serial0/0/0:0 701
>!
>interface Serial3/2
>no ip address
>encapsulation frame-relay
>clockrate 2000000
>frame-relay intf-type dce
>frame-relay route 307 interface Serial0/0/0:0 703
>!
>interface Serial3/3
>no ip address
>shutdown
>!
>interface Serial3/4
>no ip address
>shutdown
>!
>interface Serial3/5
>no ip address
>shutdown
>!
>interface Serial3/6
>no ip address
>shutdown
>!
>interface Serial3/7
>no ip address
>shutdown
>!
>router isis
>net 49.0000.0002.0002.0002.00
>!
>ip kerberos source-interface any
>ip classless
>no ip http server
>!
>!
>!
>alias exec ip sh ip route
>alias exec ipx sh ipx route
>alias exec int sh ip int brief
>!
>line con 0
>exec-timeout 0 0
>transport input none
>line aux 0
>line vty 0 4
>login
>!
>end
>
>r2#ip
>Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter
>area
> * - candidate default, U - per-user static route, o - ODR
> P - periodic downloaded static route
>
>Gateway of last resort is not set
>
> 172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
>C 172.16.20.0/28 is directly connected, Ethernet0/1/0
>C 172.16.70.0/30 is directly connected, ATM1/0.1
>i L2 172.16.70.4/30 [115/20] via 172.16.70.2, ATM1/0.1
>
>
This archive was generated by hypermail 2.1.4 : Thu Jun 20 2002 - 22:33:14 GMT-3